1. Field
The invention relates to fluid filtering systems and, in particular, to systems for filtering material as small as one micron or less from a liquid.
2. State of the Art
Filtering systems for removal of macroscopic sediment and particles from fluids are well known in the art. Self-cleaning filters which utilize programmed backwashing of the filter media have also been proposed. See, for example, U.S. Pat. Nos. 2,632,566; 2,828,017; and 3,388,799. Electrical precipitation of contaminants from gas and liquid streams are known. Only recently however, has it been suggested to utilize an electrical or electromagnetic field in combination with a filter media for removing microscopic contaminants from liquids. Microscopic suspended and dissolved contaminants are effected by the polarization and oxidation of the electrical field to coagulate or coalesce into larger particles which are entrapped and removed from the fluid by the filter media.
3. Objectives
A principal objective of the present invention is to provide an improved filter system which achieves maximum benefits from the electrical mechanical operation of the filter. A further objective is to provide a filter system capable of filtration of particles as small as about 0.2 micron from the fluid being filtered. An additional objective is to provide such a filter system which operates at a high flow capacity and is readily regenerated and self-cleaned by being backwashed. A further objective is to provide a filter system in which the filter media is selectively compressed so as to control its density during the filter cycle, with decompression and expansion of the filter media being achieved during the backwash cycle whereby rapid, efficient regeneration of the filter media is obtained.